Category Archives: Development

Something about the cord clamping debate has troubled me for quite some time now. Long after early cord clamping (ECC) was shown to be of no benefit to either mother or baby, and in fact may harm the baby through loss of iron during a critical period of brain development, some in the obstetrics community wanted to see more evidence before endorsing delayed cord clamping (DCC) for healthy term babies. The pro-DCC evidence was theoretical, they claimed; before they agreed to wait a couple of extra minutes to clamp the cord, they wanted hard proof that DCC actually helps babies.

The logic behind this foot-dragging—“We’re not abandoning a pointless practice without a darned good reason,” more or less—escapes me. After all, this isn’t like switching from one way of transplanting hearts to another. DCC doesn’t require new equipment or extensive training, and it’s not a budget-buster, either. You simply wait 2 or 3 minutes to clamp the cord, instead of doing it right at birth. It’s not brain surgery.

Well, there’s finally some solid evidence for the hard-to-convince, pro-ECC crowd. In a recently published randomized clinical trial, a Swedish research team led by Dr. Ola Andersson discovered that a group of healthy children who had been randomized to receive DCC (3 minutes after birth) had significantly better personal-social and fine-motor functioning at 4 years of age than did those who were randomized to receive ECC (< 10 seconds after birth). The effect was more marked in boys than in girls.

Andersson and colleagues checked the children’s iron stores at several points and found that, while DCC babies had more total body iron at 4 months of age, the ECC/DCC difference disappeared by 12 months of age. Looking at neurodevelopment, they found no differences between ECC and DCC babies at 12 months, but by 4 years the DCC children showed significant developmental advantages over the ECC group. It seems like an odd finding: how could a DCC-related “bump” in iron stores in early infancy cause developmental differences at 4 years but not at 12 months?

It likely comes down to an inadequate supply of iron at a critical time in neurodevelopment—those first few months, when many of the brain’s critical neural pathways are established. The resulting delays weren’t detectable with the kind of screening that can be done on a 12-month old, but by 4 years of age more extensive testing could pick it up.

The most important thing about this study is that it was a randomized clinical trial, a study design that can show that “a” is directly connected to “b”. The researchers in this case took two evenly matched groups of infants, randomly assigned them to different treatments (DCC or ECC), and then measured the relevant outcomes (iron stores + developmental differences). While there are some shortcomings to the study—the number of kids involved isn’t huge, for example—the findings fit with what’s currently known about the effects of iron deficiency in early childhood.

This study presents a solid argument in favor of DCC. And if that’s not enough to sway ECC advocates, what is?

More on iron metabolism (and why boys are affected more than girls) in upcoming posts…

The subject? Prenatal treatment of congenital adrenal hyperplasia (CAH), a rare inherited defect in hormone production that leads to an overproduction of male hormones in utero. CAH can cause deformity of the developing female genitalia (male genital development is unaffected), and can also lead to more “masculinized” behavior in affected girls and women. Though most are heterosexual, women with CAH are more likely to be lesbian or bisexual than the general population.

Other critics point out that very few affected girls really need the very aggressive genital surgery performed in the past, and that very high doses of prenatal steroids appear to increase the risk of serious consequences for treated children, including poor growth, learning disabilities, and even mental retardation. Such alarming reports have led many researchers in the United States and Europe to call for an end to the practice.

Still, Dr. Maria New, a pediatric endocrinologist in New York–by far the most prominent advocate of prenatal treatment–has declared the practice to be effective and “safe for mother and child.” Problem is, she and her colleagues haven’t been very diligent in following the babies they’ve treated over the last three decades, so the real risks of the prenatal steroid therapy aren’t yet completely known.

There’s much more detail in the post, and if you’re not feeling science-y enough to tackle that one, fear not. I’ll be back with lighter fare soon!

PS: Even if you’re not feeling science-y today, head to OBOS and donate money to that very worthy organization! Start racking up those 2013 tax deductions!

The second study (following up on my last post), also published in Pediatrics, involves a comparison between soy formula and cow’s milk formula. The concern: given the known differences in cognitive development between breast and formula-fed babies, does soy pose any additional risks when compared with cow’s milk formula?

The authors, Aline Andres and colleagues at the University of Arkansas, focused on the role of isoflavones, an estrogen-like chemical found in soy. Their results: there was no difference in behavioral, psychomotor, and language development in the soy-fed babies compared with those who drank cow’s milk formula.

But…what they did find (again) is that neither the soy nor the cow’s milk groups did as well on testing as did breastfed babies. This difference held up even after mother’s age, socio-economic status, and IQ were taken into consideration.

So what is the deal about breastfeeding and better scores (or should I say formula feeding and lower scores)? More on that subject down the road…

A number of studies in the past decade have shown that breastfed babies are slightly “smarter” than those who are formula-fed, at least in terms of standard intelligence test scores. Which, of course, has led to a predictable, lengthy media spat as to why this might be so.

Is the “IQ gap” due to some unknown smartness-inducing quality of breast milk itself? Or some IQ-damaging substance in formula? Or might it be due to some other factor altogether–like the extended mother-baby contact that comes with nursing, or the fact that the breastfeeding mothers in the studies tended to have higher IQs themselves, and more money, than the formula-feeding moms?

A couple of recently published studies don’t settle that issue, but do show how incredibly difficult it is to make infant formula that comes anywhere close to providing all the benefits that breast milk and breastfeeding do.

The first study*, published by Ahmad Qawasmi and colleagues in Pediatrics on May 28, looks at two fatty acids, abbreviated DHA and AA, which are added to infant formula. DHA and AA are long-chain polyunsaturated fatty acids known to be critical to cognitive development both within the womb and in early childhood. Breast milk contains substantial amounts of DHA and AA; formula did not until supplementation began some years ago. Formula manufacturers quickly trumpeted the benefits of these new additives to infant brain growth. And though they didn’t say so directly in their ads, they hoped that DHA and AA would close the IQ gap between their products and breast milk.

It didn’t work out that way. According to Qawasmi’s team, which performed a meta-analysis of a dozen studies on the subject, the addition of DHA and AA to formula provided no measurable “intelligence boost” at one year of age compared with un-supplemented formula.

That’s not to say that DHA and AA shouldn’t be added to infant formula–anything that brings the composition of formula closer in line with breast milk is a good thing for the 70% of American babies who are drinking at least some of it by the age of six months.

It’s just that we’ll have to look elsewhere for the answer to the differences in cognitive development between breast and formula babies. Qawasmi suggests that other factors should be studied, such as the antimicrobial, anti-inflammatory and immune-boosting properties of breast milk.

What this and other studies do demonstrate, though, is that it’s pretty darn tough (and likely impossible) to commercially duplicate all the benefits of breastfeeding. After millions of years of tinkering, nature knows what it’s doing.

(*A look at the second study, about soy formula and cognitive development, is coming up…)

How do babies decide what to concentrate on as they learn the ways of the world? And how do they keep from being overwhelmed by a world in which everything is new? Surprisingly (or maybe not), they act a lot like adults.

Writing in the journal PLoS ONE, Celeste Kidd and colleagues at the University of Rochester describe how babies learn: they use a “principled inferential process” and “appear to allocate their attention in order to maintain an intermediate level of complexity.”

Say what?

Fortunately Kidd saves the day by naming the process “the Goldilocks Effect.” (Quick refresher: Goldilocks stumbles into the bears’ cottage, finds their porridge to be either too hot or too cold, whines about her porridge-fate until she finally discovers a warm-ish bowl that’s “just right.” She eats it, settles into a “just right” bed, and goes to sleep. When the bears return they do not eat her, for reasons I’ve never quite understood.)

Kidd found that babies tend to spend most of their visual attention on things that are neither too simple nor too complicated. That is, they are attracted to “just right” complexity–enough to stimulate their brains, but not so dull as to put them to sleep, or so complex as to fry their little noggins.

This study confirms what many parents have long known: babies will seek out the level of stimulation in their environment that is appropriate to their learning needs. Bombarding them with extra, too-complex stimulation doesn’t accomplish much, other than to overwhelm them.

Watch a baby and you’ll know how much stimulation is too much. They simply look away when they’ve had enough. Kind of like me in my college calculus class…

If you’re a fan of TED talks, here’s a short, interesting one by Alison Gopnik. She’s a professor of psychology at UC Berkeley and the author of popular books on how babies learn–most recently The Philosophical Baby (2009), which I reviewed for the San Francisco Chronicle. Her books make for fascinating reading, if you find babies as fascinating as I do.

In the Ted talk and in her book Gopnik describes infants and toddlers as having a “lantern consciousness” with which they explore their world. They take in everything around them–like a lantern casting light in all directions–without doing much editing. That maddening tendency to flit from thing to thing may drive parents nuts, but it’s purposeful flitting–it’s how they eventually make sense of everything, from social encounters to the physics of walking. (There’s a very cute video in the talk of a four-year old trying to figure out how to make a block light up–if nothing else, check that out.)

By comparison, Gopnik describes adults as having “spotlight consciousness”–we’re really good at zeroing in on the task at hand, at the expense of missing out on a lot of interesting things going on around us. We do occasionally flip into “lantern” mode, like when we travel to a new place and explore the differences between there and home (if we have time to just wander, that is). But most of the time we burrow into our familiar routines, focused on schedules and deadlines and racing through our chosen mazes. Too bad for us!

I like her description of what it’s like to be a lantern-conscious baby:

Pass the espresso!

“It’s like being in love in Paris for the first time after you’ve had three double espressos.”

Think of that image the next time you watch a baby hard at work, figuring out the world.

This is one for the “Research Done by People Who Must Not Have Kids of Their Own” file…

Researchers at the University of Colorado, Boulder, recently discovered that toddlers deprived of naps tend to be crabbier than their “napped” peers, and do more poorly at puzzles and such. (Well, huh! My mother could have told them that.) The Boulder-ites speculate that tired, crabby toddlers may grow up to be tired, crabby adults, too. Check back in 20 years for an update on that one.

In the meantime, stay tuned for the next study from the U of C: “Hungry Toddlers Can Be Quite Unpleasant.”